A novel actinomycete, designated strain NEAU-ycm1(T), was isolated from an edible Chinese black ant (Polyrhachis vicina Roger) and characterized with a polyphasic approach. The organism was found to have morphological and chemotaxonomic characteristics typical of streptomycetes. Phylogenetic analysis based on the almost complete 16S rRNA gene sequence show that the novel isolate belongs to the genus Streptomyces and forms a separate subclade. The closest phylogenetic relatives were identified as the type strains of Streptomyces intermedius NBRC 13049(T) (97.74 %), Streptomyces aureoverticillatus NRRL B-3326(T) (97.69 %), Streptomyces rutgersensis NBRC 12819(T) (97.68 %), Streptomyces gougerotii NBRC 3198(T) (97.68 %) and Streptomyces diastaticus subsp. diastaticus NBRC 3714(T) (97.68 %). Similarities to other type strains of the genus Streptomyces were lower than 97.55 %. A comparison between strain NEAU-ycm1(T) and the closest related Streptomyces type strains revealed that it is different from them in morphological, physiological and biochemical characteristics. Therefore, it is proposed that NEAU-ycm1(T) (=CGMCC 4.7094(T) = DSM 42102(T)) represents a novel species of the genus of Streptomyces, for which the name Streptomyces polyrhachii sp. nov. is proposed.